Donnellan's distinction between attributive and referential uses of definite descriptions is extended to include Lewis' basic categories. The distinction as applied to sentences is brought out by investigating the consequences of the failure of presupposed sentences. Stalnaker uses Donnellan's distinction to support his theory of creating an intensional level between those of interpreted sentences and extensions. This intensional level consists of functions taking only possible words as input and giving the extension as output. Therefore, by extending Donnellan's distinction more support is given to Stalnaker. (Author)